JPH03254581A - Exposure control mechanism for camera - Google Patents

Abstract

PURPOSE:To complete photometry with twice exposures by executing the exposure so that the brightness range of the approximate middle of an AE movement range becomes an optimized level, obtaining the information of the brightness of the whole image pickup screen and general brightness distribution information from the data of the number of picture elements scattered white and defaced black and determining exposure conditions. CONSTITUTION:When a releasing switch 23 is half-depressed, a camera action control means 21 controls an iris mechanism 2 and a shutter 3 to satisfy conditions to cover the medium brightness range of an AE movement range and executes the first exposure. A brightness signal (Y) obtained by the exposure is inputted to a number of picture elements counting circuit which consists of comparators 18a to 18n and counters 19a to 19n and an output value is inputted to an evaluation value counting means 22. When an obtained video signal has a lot of white scattered parts, the camera action control means 21 shifts an exposure under as a second exposure conditions and obtains precise picture element information of a high brightness part. Thus, photometry is completed with the twice exposures.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an exposure control mechanism for a camera, and in particular to a still video camera that can record an image signal obtained using a solid-state image sensor such as a CCD on a floppy disk or the like. This invention relates to a camera exposure control mechanism.

(Background of the Invention) There are various types of exposure control mechanisms for cameras, and silver halide cameras generally have a sensor dedicated to photometry, which performs photometry.

In a still video camera, the output signal of the image sensor is generally integrated, and if the value is small, the iris is opened wide, and if the value is large, the iris is closed, thereby controlling the signal using a negative feedback loop.

In addition, the inventor of the present application has previously proposed an exposure control mechanism in which pixels are classified according to their brightness values, a brightness histogram is created based on the number of classified pixels, and the optimal exposure conditions are determined from this brightness histogram. (Special application 1986-1970)
409).

(Problems to be Solved by the Invention) Among the above-mentioned exposure control methods, those that use a dedicated sensor have difficulty controlling exposure with high precision because the sensitivity of the sensor and the sensitivity of the image sensor vary.

The control method using a negative feedback control loop using an image signal changes the iris little by little while looking at the integral value of the image signal, so it takes time to reach the appropriate level, and when shooting still images, the shutter Problems such as missed opportunities may occur.

The exposure control method previously proposed by the inventor of this application controls the exposure so that the brightness level of the part that occupies a large area of the image capture screen or the appropriate image capture signal level is used to accurately grasp the main subject. This method has an excellent effect of being able to perform the following steps, and is sufficiently durable for practical use.

However, when the inventor of the present application conducted further studies with the intention of improving the performance of the camera, the following problems to be improved became clear.

That is, when creating a brightness histogram by classifying pixels on the imaging screen by brightness level, a pixel distribution histogram is created over the entire brightness range in which exposure can be controlled. Since multiple exposures are required, photometry takes that much time and responsiveness deteriorates.

This is the brightness range of the brightness histogram (AE linked range)
Usually ranges from 7 to 18 Lv, and in order to obtain pixel distribution data over this entire luminance range, it is necessary to perform exposure multiple times under different exposure conditions.

The present invention has been made in view of the above-mentioned problems, and
The purpose of the present invention is to provide an exposure control mechanism for a camera that is capable of highly accurate and quick-response photometry.

(Means for Solving the Problems) An exposure control mechanism for a camera according to the present invention includes an image sensor, an exposure amount adjustment means for adjusting the exposure amount of the image sensor, and an operation of the exposure amount adjustment means. The exposure control means includes an exposure amount control means and a brightness information acquisition means for acquiring brightness information of an imaging screen based on a brightness signal obtained from the image sensor, and when performing exposure control, the exposure control means first controls the exposure. A first exposure is performed by controlling the amount adjusting means to adjust the exposure to a luminance range approximately in the middle of a luminance range in which exposure can be controlled, and the luminance information acquiring means Based on the luminance signal, distribution data of pixels on the imaging screen with respect to the luminance level is obtained, and from this, the total amount of pixels in each of the blown-out highlights and blown-out shadows is determined and notified to the exposure control means, and the exposure control unit Based on the notified distribution data, the means controls the exposure amount adjusting means to perform exposure while changing the exposure amount until the amount of the blown-out highlights and the blown-out shadow portions becomes less than a predetermined value. let it be done,
When the amount of blown-out highlights and blown-out shadows becomes less than the predetermined value, the exposure is terminated even if luminance information is not obtained for the entire luminance range in which exposure can be controlled, and the data obtained at the end of this exposure is The present invention is characterized in that the exposure amount adjusting means is controlled so that the luminance range having a large evaluation value created based on the above has an appropriate signal level, and final exposure control is executed.

In addition, the exposure amount control means is an optical sensor provided to be used for purposes other than automatic exposure control, such as a distance measurement sensor or an auto white balance sensor, instead of executing the first photographing. Information about the brightness of the subject is obtained from the signal, and if it is determined that the subject is bright by comparing it with a predetermined reference value, exposure is performed with a lower exposure than the exposure amount corresponding to the reference value. and when it is determined that the subject is dark, the exposure is performed under conditions where the exposure is increased from the exposure amount corresponding to the reference value.

(Operation) If the AE interlocking range is 7 to 18 Lv, a complete brightness histogram cannot be created unless exposure is performed at least three times. However, in reality, it is sufficient to perform accurate exposure control if luminance information can be obtained for most pixels in the screen and a luminance histogram of a predetermined level or higher can be created. That is, information about the entire luminance range is not necessarily necessary, and sufficient exposure control can be performed as long as the total number of pixels for which luminance information is not obtained is equal to or less than a predetermined reference value.

Based on such consideration, in one example of the present invention, first, A
The first exposure is performed so that the luminance range approximately in the middle of the E-linked range is at the optimum level. Specific pixel number data (pixel distribution data) can be obtained through this exposure only in the intermediate luminance range mentioned above, or because the total number of pixels is predetermined, the total amount of blown-out pixels (i.e., the exposure It is important to know the total number of pixels whose image signal is saturated due to strong exposure) and the total number of pixels with blackout (the total number of pixels where the exposure is too weak and only a weak image signal is obtained and it can only be determined as black). can.

The exposure control means acquires information on the overall brightness of the image capture screen and approximate brightness distribution information from the data on the number of pixels with blackout and blackout, and the exposure control means sets the second exposure condition based on the information. decide.

As a result, except for imaging under special conditions, necessary pixel distribution information can be obtained in most cases, and photometry can be completed with two exposures.

In another example of the present invention, rough information regarding the brightness of the imaging screen is obtained from a sensor used for other purposes, and the first exposure conditions are determined based on that information (i.e. (If the object looks bright, perform exposure at higher brightness, and if it looks dark, perform exposure at lower brightness.) By doing so, it is possible to complete photometry in one exposure. At worst, photometry can be completed in two exposures.

Further, in another example of the present invention, exposure for photometry is continued without changing the exposure amount until the total amount of overexposed and overexposed pixels becomes equal to or less than a predetermined value. As a result, even if the subject exists over a wide luminance range, the accuracy of the luminance histogram to be created can be guaranteed, and the effects of the present invention can be obtained no matter what the subject is. can.

(Example) Next, an example of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a block diagram of one embodiment of the exposure control mechanism of a camera according to the present invention (this diagram is also commonly used in other embodiments).

Overall configuration As an exposure amount adjustment mechanism, an iris device 12 is installed near the lens system 1. A shutter 3 is provided, and these are driven by an AE drive circuit 27. In addition, lens system 1
is driven by the AF motor 26.

The operations of the AF drive circuit 27 and the AF motor 26, as well as the operations of the entire camera, are collectively controlled by the CPU 20.

The CPU 20 includes a camera operation control means 21 and an evaluation value calculation means 22 as functional blocks (means for realizing a predetermined function constructed by hardware operating according to software). These functional blocks perform predetermined control when the release switch 23 is operated. That is, when the release switch 23 is pressed halfway, automatic exposure control (further distance measurement, etc.) is performed, and then when the release switch 23 is pressed fully, photographing and recording operations are performed.

A CCD (imaging device) 4 converts the optical signal of the imaging screen into an electrical signal, and the output signal of the CCD 4 is amplified by an amplifier 5.
The luminance signal processing circuit 6 and color separation circuit 7 are manually inputted.

A luminance signal processing circuit 6 generates a luminance signal (Y), and a color separation circuit 7 separates color signals. The color difference signals outputted from the matrix circuits 8.9 are encoded by the encoder circuit IO and inputted to the recording circuit 33. Further, a synchronization signal is added to the luminance signal (Y) output from the luminance signal processing circuit 6 by a synchronization signal addition circuit 11, and the recording circuit 3
3 will be done manually.

The recording circuit 33 includes an FM modulation circuit 12 and an amplifier 13, and the output of the amplifier 13 is recorded on a floppy disk 15 via a recording head 14.

When automatic exposure control is performed, the luminance signal processing circuit 6
The luminance signal (Y) output from the plurality of comparators 18a
=18n and counters 19a to 19n, which count the number of pixels carrying luminance. The inverting terminals of the comparators 19a to 19n each have a voltage (for example, 0.5
A voltage difference corresponding to a luminance difference of Lv) is input. Each of the counter circuits 19a to 19n is supplied with a clock signal CR in common, and each counter circuit operates while the outputs of the comparators 1111a to 18n are at a high level.
That is, the clock signal CR is counted while the lower limit level of each luminance range is exceeded. For still video cameras,
Since the scanning time for one screen is 1/60 seconds, the frequency of the clock signal CR is, for example, about 3.8 MHz if the screen is divided into about 60,000 pieces.

The count values of each counter 19a to 19n are
The evaluation value calculation means 22 is manually operated by the evaluation value calculation means 22 in the PU 20, and the evaluation value calculation means 22 creates a brightness histogram of the screen based on each count value, and also calculates, for example, 2Lv within the brightness range from which pixel information is obtained. The number of pixels is added within the range to calculate the evaluation value of the evaluation brightness, and the camera operation control means 21 is notified of the calculation result.

The camera operation control means 2I determines a brightness range in which the evaluation value is maximum, and controls exposure so that the imaging signal in this brightness range is at an optimum level.

Further, reference numbers 28 and 29 are respectively an LED and a light sensor for distance measurement (AF). and the distance to the subject is calculated.

In addition, reference number 30 indicates A for auto white balance.
If you have a WB sensor and perform regular AWB operation,
The switch SWI is switched to the A terminal side, and when information regarding the brightness of the subject is to be obtained (an embodiment described later), it is switched to the B terminal side. Switching of the switch SWI is controlled by the AF system drive circuit 32.

Specific example of exposure control according to the present embodiment The relationship between the output signal of the CCD (imaging device) 4 and the amount of incident light is completely proportional, and the relationship between the brightness of the imaging screen and the level of the imaging signal is, for example, as shown in FIG. (In FIG. 2, the brightness values are logarithmically compressed).

If the AE interlocking range is 8 to 16 Lv, if it is necessary to obtain complete pixel distribution information for the brightness of the imaging screen,
Three exposures must be made as shown in A, B1, and C. However, in most cases, accurate exposure control can be performed if a certain level of brightness histogram is obtained, so in this example, the first exposure is performed using the AE
The exposure is performed under conditions that cover the intermediate brightness range of the interlocking range, and the second exposure conditions are determined according to the content of the image pickup signal obtained thereby.

That is, when the release switch 23 is pressed halfway, the camera operation control means 21 controls the iris mechanism 2 and the shutter 3 so as to satisfy the conditions shown in FIG.
Execute the second exposure.

The luminance signal (Y) obtained by this exposure is input to the pixel count circuit consisting of the aforementioned comparators 18a to 18n and counters 19a to 19n, and the output value of each counter is manually input to the evaluation value calculation means 22. .

If the obtained imaging signal has many skipped parts as shown in FIG. 3(a), the brightness histogram created by the evaluation value calculation means 22 will be as shown in FIG. 4, for example. In other words, in the intermediate brightness range (10.5Lv to 13.5Lv), a histogram with an accurate number of pixels can be obtained in 0.5Lv increments, and although the details are unknown for the high and low brightness areas, It is clear that the number of pixels in high-brightness areas (that is, the number of pixels that are blown out) is large, and the number of pixels in low-brightness areas (that is, the number of pixels that are blown out) is small.

In such a case, the camera operation control means 21 selects the conditions shown in FIG. 2 as the second exposure conditions, and shifts the exposure amount to an understatement to obtain accurate pixel information of the high-brightness portion. If you create a brightness histogram by taking into account the pixel information obtained from this exposure, you can almost completely understand the pixel distribution in the main range of 10.5 to 18 Lv, and you can accurately understand the pixel distribution in the main range of 10.5 to 18 Lv, even without pixel information in the low brightness part. Exposure control is possible. That is, photometry is completed with two exposures.

As a result of the evaluation value calculation in the 2Lv range by the evaluation value calculation means 22,
For example, if the evaluation of the brightness range of I2-14Lv is the maximum, the camera operation control means 21 controls the iris mechanism 2 and shutter 3 so that the signal level in that brightness range is optimal, and the exposure control is completed. do. After this, when the release switch 23 is fully pressed, a photograph is taken.
The imaging signal is recorded on the floppy disk 15.

On the other hand, the image signal obtained by the first exposure is shown in Figure 3 (
If there are many dark areas like b), take a second shot under the conditions shown in Fig. 2 a, obtain accurate pixel information of the low-brightness areas, and perform an appropriate evaluation. Take pictures.

Control Operation Flow FIG. 5 is a flowchart for explaining the control procedure in this embodiment.

When the photographer presses the release switch 23 halfway, exposure control is started, and the first exposure is performed under the conditions shown in FIG. 2A (step 40).

Next, the image pickup signal is read out and the number of pixels for each brightness range is counted (step 4 ()), and the amount of overexposure and underexposure is determined (step 42). At this time, if there is a large amount of underexposure, the second A second exposure is performed under condition A in the figure (step 43).
), if there are many overexposures, a second exposure is performed under the conditions shown in FIG. 2 (step 44).

Next, in step 4, read out the image signal obtained by the second exposure and count the number of pixels for each brightness range.
5) Create a luminance histogram based on the obtained information (step 46).

On the other hand, in step 42, the amount of overexposure and undertones is small,
If the pixel distribution information of the main parts has already been obtained in the first shooting, perform the second exposure and create a brightness histogram (step 4B). After this, proceed to step 4 to calculate the evaluation value. 47), determine the exposure conditions based on this, step 48), and perform exposure (
Step 49), and record the obtained imaging signal on a floppy disk (Step 50).

Example 2 In the above example, the first exposure condition is uniformly set to the middle of the AE interlocking range, but if rough information regarding the brightness of the subject is obtained, the first exposure condition is set based on this information. You can decide the conditions.

In other words, if the object to be photographed is bright, the first exposure is carried out under conditions shifted to the higher luminance side than the conditions in Figure 2 A, and if it is dark, the first exposure is carried out under conditions shifted to the lower luminance side than the conditions in Figure 2 A. Make the second exposure.

The amount of exposure shift is determined, for example, from the average value of human input signals indicating the brightness of the object to be photographed. This increases the possibility that photometry will be completed in one exposure. At worst, photometry can be completed almost reliably by two exposures.

As a method for obtaining information regarding brightness, it is desirable to use detection signals from sensors used for other purposes, rather than adding a new sensor, to avoid complicating the configuration.

Therefore, in this embodiment, an active AF (autofocus) sensor 29 is used. Active AF measures distance by detecting the reflected light emitted by the infrared LED 28, as shown in the upper left of Figure 1, or by detecting the reflected light from the infrared LED 28, or by detecting the reflected light from the LED 28 to avoid the influence of surrounding light. It only detects the signal immediately after the signal is detected. Therefore, by measuring the level of the detection signal from the sensor 29 at other timings, it is possible to obtain approximate information about the surrounding brightness. 1st
In the figure, the signal line is branched before reaching the distance measuring circuit 31, the detection signal is amplified by the amplifier 34, and then converted to a digital signal by the A/D converter 35 and sent to the camera operation control means 21 in CPUGO. It can now be done directly by humans. The camera operation control means 21 compares the human power signal with a predetermined reference value (stored in the preparatory ROM 25), controls the iris mechanism 2 and the shutter 3 based on the comparison result,
Perform the first exposure.

FIG. 6 is a flowchart showing the operating procedure of this embodiment.

First, the A/D converted output signal of the optical sensor 29 is taken in (step 60) and compared with a reference value to determine the brightness (step et). At this time, if it is judged that it is dark, the exposure is adjusted to the lower luminance side than condition A in Figure 2 (
Step 62), if it is determined that it is bright, perform exposure under conditions that are more bright than condition A (step 63).
, if the brightness is determined to be intermediate, expose under the appropriate conditions (
Step 64).

Next, the signal is read out and the pixels in each luminance range are counted (step 65), and the amount of overexposure and underexposure is determined (step 66).If there is a lot of overexposure, the first exposure Perform a second exposure under conditions shifted to the lower brightness side (
Step 67), if there are many overexposures, expose under conditions shifted to the high brightness side (Step 68), read out the signal and count the number of pixels for each brightness region (Step 69),
A brightness histogram is created (step 70). If it is determined in step 66 that the amount of overexposure and underexposure is small and that the luminance distribution information of the main parts has already been obtained, a luminance histogram is created without performing a second exposure (step 70). .

Next, an evaluation value is calculated (step 71), exposure conditions are determined (step 72), and exposure is performed (step 7).
3) Record the imaging signal on a floppy disk (step 74).

Embodiment 3 In this embodiment, information regarding the brightness of the object to be imaged is obtained from the AWB sensor 30 for automatic white balance adjustment.

Auto white balance is an adjustment that uses the smoothing circuit 16 and white balance circuit 17 to make the level difference of the color difference signals output from the matrix circuit 8° 9 zero. The switch SWI shown at the upper left of FIG. 1 is switched to the A terminal side under the control of the AF system drive circuit 32. On the other hand, in this embodiment, when acquiring brightness information, the switch SWI is switched to the B terminal side.

The signal obtained from the AWB sensor 30 (absolute value signal combining each color) is amplified by an amplifier 36, and then sent to an A/D converter 37.
The data is converted into digital data and manually inputted to the camera operation control means 21 within the CPU 20. Camera operation control means 21
performs control operations according to the flowchart of FIG. 6 described above to perform exposure control.

Example 4 In this example, information regarding the brightness of the object to be imaged is obtained from a passive AF sensor (not shown).

A passive AF sensor forms an image of a subject on the sensor, and determines the distance M from the blur or positional deviation of the image. In this embodiment, the brightness of the object can be estimated from the signal level of the sensor and the integration time of the sensor required to obtain the signal.

Embodiment 5 As described above, in most cases, exposure for photometry only needs to be carried out once or twice, but it is not always necessary to complete the exposure in just two times. Basically, it is best to decide whether to continue or end exposure for photometry depending on whether there are pixels for which accurate brightness information could not be obtained in previous exposures or whether there are still pixels remaining.

For example, if the camera specifications require coverage up to 19Lv, starting with an exposure set to 10.5Lv - 13.5Lv will not cover the range with just two exposures if the subject is very bright. If there are any skips left, you will have to expose again.

For example, in the case of an object in the state shown in FIG. 7, there are many blown out highlights and blown out shadows in the first exposure under intermediate conditions. In such a case, if one selects the one that is even slightly larger and exposes it by changing the exposure conditions, information on the other luminance range will be ignored, and accurate judgment cannot be made. In this case, it is desirable to perform exposure in accordance with the other.

The operational flow of the camera operation control means 21 when performing such control is shown in FIGS. 8 and 9.

In FIG. 8, steps 43 and 44 in FIG. 5 above are replaced with steps 80 and 81, respectively, and steps 45 and 46 are separated,
In addition, a feedback loop returning from step 45 to step 42 is added. Similarly, Figure 9 shows the above-mentioned 6
Steps 67 and 68 in the figure are replaced with steps 90 and 91, respectively, steps 69 and 70 are separated, and a feedback loop returning from step 69 to step 66 is added.

In this embodiment, if the self-skipping is larger, the second exposure is performed in accordance with the higher brightness side. As a result, brightness information is obtained for pixels on the high brightness side. Comparing the pixels that are blown out in the shadows in both cases and the pixels that are blown out in the highlights in both of these two exposures, the number of pixels with blown out shadows is quite large, so next, perform an exposure that matches the low brightness side. It turns out. In this case, the previous two exposure conditions are memorized, and the exposure is performed with the brightness lower than those conditions. Exposure for photometry is performed until the amount of blackout is less than a predetermined value (until the necessary information is obtained), and once the information necessary to create a brightness histogram is obtained, the entire brightness range is Exposure ends even if no information is obtained.

(Effects of the Invention) As explained above, according to the present invention, the following effects can be obtained.

(1) Eliminating the conventional idea of creating a pixel distribution histogram over the entire luminance range, information on the entire luminance range is not necessarily necessary, and the total number of pixels for which luminance information is not obtained is below a certain standard. By adopting a new photometry method that assumes sufficient exposure if a histogram of a predetermined level or higher can be created, the accuracy of the brightness histogram can be maintained at a predetermined level or higher for any imaging screen. At the same time, it is possible to shorten the photometry time.

(2) In a mechanism that performs multiple shots with different exposure conditions, creates a brightness histogram from the image signal, performs photometry, and controls exposure, the first exposure is performed in accordance with the intermediate brightness range of the AE interlocking range, By configuring the configuration to determine the conditions for the second exposure based on the results, in the case of Hatonto, it is possible to complete metering with two exposures, maintaining the accuracy of exposure control and improving the responsiveness of the camera. It is possible to improve the effectiveness of the system.

(3) Also, information regarding the brightness of the imaging screen can be obtained from sensors used for other purposes, and based on that information,
By determining the conditions for the second exposure, you can increase the possibility of completing the photometry with one exposure, or at worst, ensure that the photometry is completed with two exposures, maintaining the accuracy of exposure control. At the same time, the camera's responsiveness can be improved.

(4) With these effects, it is possible to provide a camera that can obtain clear images without missing a photo opportunity.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an embodiment of the camera control mechanism of the present invention, Fig. 2 is a diagram showing the characteristics (relationship between brightness and signal level) of a CCD (imaging device), and Fig. 3 ( a) and (b) are diagrams showing an example of the state of the imaging signal obtained by photometry, and Fig. 4 shows the luminance created based on the imaging signal obtained by the first exposure in the first embodiment. FIG. 5 is a flowchart showing a control procedure in the first embodiment; FIG. 6 is a flowchart showing a control procedure in the second and third embodiments. FIG. 7 is a diagram showing an example of the brightness distribution of the image capturing screen, and FIGS. 8 and 9 are flowcharts showing the operating procedure of the fifth embodiment. 1. Lens system 2. Iris mechanism 3. Shutter 4. CCD (imaging device) 5.
Amplifier 6... Luminance signal processing circuit 7...
Color separation circuit 8.9... Matrix circuit 10... Encoder circuit 11... Synchronization signal addition circuit 12... FM modulation circuit i3... Amplifier 14. Recording head 15...
Floppy disk 16... Smoothing circuit 17... White lance circuit 18a-18n... Comparator 19a-19n.
...Counter 20...CPU 21...Camera operation control means 22...Evaluation value calculation means 23...Release switch 24...RAM25...
...ROM 2B...AF motor 27.
...AE drive circuit 28...LED29...Active AE optical sensor 30...AWB sensor 31...Distance measurement circuit 32
...AF system drive circuit 33...recording circuit 34...
・Amplifier 35...A/D converter 36...
Amplifier 37... A/D converter Fig. 5

Claims (2)

[Claims] (1) An image sensor (4), an exposure amount adjustment means (2, 3) for adjusting the exposure amount of the image sensor (4), and controlling the operation of the exposure amount adjustment means (2, 3). Exposure amount control means (21, 26, 27) and brightness information acquisition means (18, 1) that acquires brightness information of the imaging screen based on the brightness signal (Y) obtained from the image sensor (4).
9, 20, 21, 22, 24, 25), and when performing exposure control, the exposure control means (21, 26, 2
In 7), first, the exposure amount adjusting means (2, 3) is controlled to perform a first exposure by adjusting the exposure to a luminance range approximately in the middle of the luminance range in which exposure can be controlled, and acquire the luminance information. Means (18, 19, 20, 21, 22
, 24, 25) obtain pixel distribution data of the image capture screen with respect to the luminance level based on the luminance signal (Y) obtained from the first photographing, and thereby detect blown out highlights and blown out shadows. The total amount of each pixel is calculated and notified to the exposure control means (21, 26, 27), and the exposure control means (21, 26, 27) thereafter calculates the amount of overexposure based on the notified distribution data. The exposure amount adjusting means (
Exposure is performed while changing the exposure amount by controlling 2 and 3), and when the amount of blown-out highlights and blown-out shadows becomes less than the predetermined value, brightness information is obtained for the entire brightness range in which exposure can be controlled. The exposure amount adjusting means (2, 3) terminates the exposure even if the exposure is not completed, and adjusts the brightness region with a large evaluation value created based on the data obtained at the end of the exposure to an appropriate signal level. A camera's exposure control mechanism that controls the camera and performs final exposure control. (2) The exposure amount control means (21, 26, 27) is used for other purposes other than automatic exposure control, such as a distance measurement sensor or an auto white balance sensor, instead of performing the first shooting. Information about the brightness of the subject is obtained from the signal of a light sensor installed as much as possible, and when it is determined that the subject is bright by comparing it with a predetermined reference value, the exposure is set to be lower than the exposure amount corresponding to the reference value. Exposure control for a camera according to claim 1, wherein the exposure is executed under a reduced condition, and when it is determined that the subject is dark, the exposure is executed under conditions where the exposure is increased from the exposure amount corresponding to the reference value. mechanism.